Magnesium oxalate is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

comprising a

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

with a 2+ charge bonded to an oxalate

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

. It has the chemical formula MgCO. Magnesium oxalate is a white solid that comes in two forms: an anhydrous form and a dihydrate form where two water molecules are complexed with the structure. Both forms are practically insoluble in water and are insoluble in organic solutions.

Natural occurrence

Magnesium oxalate has been found naturally near Mill of Johnston, which is located close to

Insch Insch () is a village in the Garioch, Aberdeenshire, Scotland. It is located approximately from the city of Aberdeen. History Insch is home to the Picts, Pictish Picardy Stone which is one of the oldest Pictish stone, Pictish symbol stones ...

in northeast Scotland. This naturally occurring magnesium oxalate is called glushinskite and occurs at the

lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...

/rock interface on serpentinite as a creamy white layer mixed in with the

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...

e of the lichen fungus. A

scanning electron micrograph A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that ...

of samples taken showed that the crystals had a pyramidal structure with both curved and striated faces. The size of these crystals ranged from 2 to 5 μm.

Synthesis and reactions

Magnesium oxalate can by synthesized by combining a magnesium salt or ion with an oxalate. : Mg²⁺ + CO²⁻ → MgCO A specific example of a synthesis would be mixing Mg(NO₃)₂ and KOH and then adding that solution to dimethyl oxalate, (COOCH₃)₂. When heated, magnesium oxalate will decompose. First, the dihydrate will decompose at 150 °C into the anhydrous form. : MgCO•2H₂O → MgCO + 2 H₂O With additional heating the anhydrous form will decompose further into

magnesium oxide Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...

and carbon oxides between 420 °C and 620 °C. First,

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

and magnesium carbonate form. The carbon monoxide then oxidizes to

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

, and the magnesium carbonate decomposes further to magnesium oxide and carbon dioxide. : MgCO → MgCO + CO : CO + 1/2 O₂ → CO₂ : MgCO → MgO + CO₂ Magnesium oxalate dihydrate has also been used in the synthesis of nano sized particles of magnesium oxide, which have larger surface are to volume ratio than conventionally synthesized particles and are optimal for various applications, such as in

catalysis Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

. By using a sol-gel synthesis, which involves combining a magnesium salt, in this case magnesium oxalate, with a gelating agent, nano sized particles of magnesium oxide can be produced.

Health and safety

Magnesium oxalate is a skin and eye irritant. If inhaled, it will irritate the lungs and

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It ...

s. Magnesium oxalate has no known chronic effects nor any carcinogenic effects. Magnesium oxalate is non-flammable and stable, but in fire conditions it will give off toxic fumes. According to OSHA, magnesium oxalate is considered to be hazardous.

References

{{DEFAULTSORT:Magnesium oxalate Oxalates Magnesium compounds Inorganic compounds

Natural occurrence

Synthesis and reactions

Health and safety

See also

References